diff --git a/Dockerfile.builder b/Dockerfile.builder
index f1bb8dd..d16e240 100644
--- a/Dockerfile.builder
+++ b/Dockerfile.builder
@@ -5,12 +5,18 @@
 
 FROM mcr.microsoft.com/dotnet/sdk:9.0
 
+# nodejs is required by the runner itself, not by the build: actions/checkout and
+# actions/cache are JavaScript actions, and the runner execs `node` inside this
+# container to run them. Without it every job fails at the checkout step with
+# "exec: node: executable file not found in $PATH".
 RUN apt-get update && apt-get install -y \
     python3 \
     python3-pip \
     git \
     jq \
     curl \
+    nodejs \
+    npm \
     && rm -rf /var/lib/apt/lists/*
 
 RUN pip install --break-system-packages jprm
diff --git a/Jellyfin.Plugin.WatchedTogether.Tests/LibraryAccessTests.cs b/Jellyfin.Plugin.WatchedTogether.Tests/LibraryAccessTests.cs
index 6f60b0a..df73a18 100644
--- a/Jellyfin.Plugin.WatchedTogether.Tests/LibraryAccessTests.cs
+++ b/Jellyfin.Plugin.WatchedTogether.Tests/LibraryAccessTests.cs
@@ -78,7 +78,11 @@ public class LibraryAccessTests
 
         var result = service.ComputeIntersection([alice.Id, bob.Id]);
 
-        Assert.Equal([Shows, Kids], result.OrderBy(g => g).ToList().OrderBy(g => g).ToList());
+        // The intersection is a set: assert on membership, not on ordering. The library ids are
+        // random GUIDs, so any order-sensitive assertion would pass or fail by luck of the draw.
+        Assert.Equal(2, result.Count);
+        Assert.Contains(Shows, result);
+        Assert.Contains(Kids, result);
         Assert.DoesNotContain(Movies, result);
         Assert.DoesNotContain(Adult, result);
     }